Promises of cures of a wide variety of diseases or tissue injuries by specific replacement of damaged or malfunctional tissues by use of totipotent, pluripotent or multipotent stem cells is on the horizon in clinical practice (see, e.g., Fuchs, et al., 2000, Cell, 100:143-156; Weissman et al., 2000, Cell, 100:157-168; Blau, et al., 2001, Cell, 105:829-841). To transmute a somatic cell into the variety of cell types needed for tissue regeneration and reconstruction in vertebrates is a realistic goal. In fact, tissues that were formerly considered incapable of extensive regeneration, such as brain, spinal cord, and cardiac muscle, now appear to be capable of reconstruction functionally, at least to some extent, by stem cell populations. Stem cells derived from the embryo and from adult tissues have been shown to have extensive potentials for self-renewal and differentiation. However, methods of targeting of stem cells to specific target tissues and their potential value for use in tissue reconstruction procedures require further study. Investigation in these areas may lead to realistic approaches in the future for stem cell therapy in a variety of human diseases, tissue injuries, and other clinical problems. In addition, efforts in tissue engineering and restorative surgery would be improved by advances in cell targeting technology. One of the cornerstones/obstacles in implementing this technology is being able to direct the cells or tissue, engineered in vitro, to the precise in vivo site were repair is needed.